Human echolocation in different situations and rooms

Abstract

People, especially when blind, use echolocation to detect obstacles, orient themselves, and get an awareness of their environment. I and coworkers have, with mostly psychophysical methods, studied perceptual aspects of how people accomplish echolocation. Echolocation with long canes while walking was possible but difficult. The effects of the spectral composition of the emitted sounds had no effects. Sound recordings in anechoic and conference rooms from non-walking, static situations, later presented in a laboratory showed a better performance in an ordinary room with reflections, than in an anechoic room. We also found that there was a higher performance with longer sounding sounds than for short clicks. Among the difficulties for the blind are how to avoid masking of sounds. A few blind are exceptionally high performing. An “information-surplus principle” has been proposed. Various information sources are used, but repetition pitch seems more important than loudness for echolocation. Among other sources, timbre may also provide information. There may exist a time gap, acoustic gaze, for how blind people use clicks. It is likely also that there are at least two processes taking place in the hearing system when listening for echoes, one attuned to short sounds and one to long sounds.